U.S. Pat. No. 4,747,645, RUDZKI a weathering and fading resistance test instrument which provides for accurate adjustment of a defined radiation spectrum that encompasses ultraviolet (UV) radiation, infrared (IR) radiation and visible light, by means of a xenon radiation source. The system has at least two sectors from which the radiation emerges: UV mirrors that are impermeable to UV radiation, as well as a UV filter and at least one IR filter that are permeable to visible light. Each of the sectors is associated with one xenon radiation source; the filter/radiation source system is surrounded first by a quartz inner cylinder with a selectively reflective layer for IR that is permeable to UV and visible light, and an adjacent water jacket which absorbs long-wave IR radiation, then by a quartz outer cylinder, and finally by a three-piece sealing jacket made of US special glass or window glass. By means of this illumination system, it is possible to damp the intensity of given spectral components in a targeted fashion, or to vary and set the ratio of the ultraviolet to the infrared components purposefully, which is especially important for materials testing.
It is also known from the book entitled "Ultraviolete Strahlen" [Ultraviolet Radiation] edited by Jurgen Kiefer and published by Verlag Walter de Gruyter, Berlin and New York, 1977, page 95, to purposefully adjust the spectral light yield of flash units for cameras and the like with a xenon filling by specifying not only the gas pressure discharge duration, but also electrical parameters such as the arc length, voltage applied, and current density. Page 90 of this same book, in the next-to-last paragraph, refers to wall-stabilized lamps for pulsed mode operation, which are suitable for materials testing and mounting. As the second paragraph on page 90 says, it is essential that the xenon discharge lamp not require any burn-in time, or in other words that it reach its full power immediately after firing; for these reasons, xenon lamps are easily modeled or used as flash units.
It is also known from the corporate brochure No. D 310 561/3C 6.89/N Ko, published 1989 by W. C. Heraeus GmbH and captioned "XENOTEST 1200 CPS," to simulate natural sunlight by means of radiation source/filter systems; page 5 of this brochure indicates the spectral energy distribution of the illumination system in comparison with global (natural solar) radiation.
U.S. Pat. No. 4,884,009, ROTHWELL & GRANT, discloses an argon gas discharge lamp in which the emission color is related directly to the duration of the current pulse. Current pulses shorter than 5 microseconds and preferably 1 microseconds are described at col. 2, line 54, as well as so-called long-current pulses between 5 and 10 microseconds; the short pulses tend to produce a glow discharge, while the long pulses produce a transition from the glow discharge to arc discharge; however, the other parameters such as the fill pressure, doping materials and filling gas are also jointly responsible for the radiation emitted. Nevertheless, this patent does not teach any possibilities for utilizing predetermined spectral components for test instruments.